In a manufacturing process of a semiconductor device, for example, an ALD (Atomic Layer Deposition) is performed in order to form various films for the formation of an etching mask and the like on a semiconductor wafer (hereinafter referred to as wafer) which is a substrate. In order to enhance the productivity of a semiconductor device, the ALD is often performed by an apparatus which rotates a rotary table holding a plurality of wafers to revolve the wafers and to allow the wafers to repeatedly pass through process gas supply regions (process regions) disposed along the circumferential direction of the rotary table. Furthermore, CVD (Chemical Vapor Deposition) is often performed in order to form the respective films mentioned above. Similar to the ALD, the film formation by the CVD may be performed by revolving the wafers.
In such a film forming process which revolves the wafers, it is required to perform film formation with high uniformity in the circumferential direction of the wafer. Thus, it is required that film formation be performed with high uniformity over the entire surface of the wafer W by forming a concentric film thickness distribution on the wafer W and performing film formation with high uniformity even in the radial direction of the wafer W. The term “concentric film thickness distribution” refers, more specifically, to a film thickness distribution in which the film thickness is equal or substantially equal in the respective positions along the circumferential direction of the wafer, which are equidistant from the center of the wafer, and the film thickness becomes different in the respective positions along the radial direction of the wafer.
However, in the film forming apparatus which revolves the wafers, the process gas is supplied along the radial direction of the rotary table. Therefore, the film thickness distribution formed on the wafer tends to become a film thickness distribution in which the film thickness changes from the center side toward the peripheral side of the rotary table. This poses a problem in that it is difficult to form a uniform film thickness distribution in the circumferential direction of the wafer. For example, there is known a film forming apparatus which forms the concentric film thickness distribution by performing CVD so that a predetermined temperature distribution is formed in the plane of a wafer. In this film forming apparatus, the wafer is not revolved during a film forming process. Accordingly, such related art is not capable of solving the aforementioned problem.
In addition, even when forming a concentric film on a wafer, there is required a method capable of realizing high reproducibility of film forming conditions and capable of controlling and adjusting film forming conditions.